Condenser microphones are known since early 20th century and have essentially not changed since then. The condenser microphones consist essentially of a back plate, which is one plate of a condenser and a transducer membrane which is spaced closely to the back plate that is the other plate of the condenser. A polarizing voltage is applied between the two plates, and the capacitance change provides the output from the device.
Throughout the prior art, the transducer membranes used are predominantly of circular shape. One example of a condenser microphone with a non circular membrane is shown in U.S. Pat. No. 3,814,864 wherein the diaphragm is broken up into many small pieces so that each attains a natural high frequency resonance above the range of sounds to be picked up with the sum total of the pieces providing an output as great as a single diaphragm with a lower impedance. This is achieved by providing a series of concentric ring contacts with a diaphragm stretched over the rings, the highest points or ridges of which lie on a convex surface, to break up the diaphragm into annular sections.
However known condenser microphones and microphone capsules suffer from more or less pronounced resonance phenomena which deteriorate the sound quality.